2011 BMW M3

VS

2011 Porsche 911

Safety Comparison

The M3 offers optional BMW Assist, which uses a global positioning satellite (GPS) receiver and a cellular system to get driving directions, remotely unlock your doors if you lock your keys in, help track down your vehicle if it’s stolen or send emergency personnel to the scene if any airbags deploy. The 911 doesn’t offer a GPS response system, only a navigation computer with no live response for emergencies.

Both the M3 and the 911 have standard driver and passenger frontal airbags, front side-impact airbags, head airbags, front seatbelt pretensioners, four-wheel antilock brakes, traction control and electronic stability systems to prevent skidding.

Warranty Comparison

The M3’s corrosion warranty is 2 years longer than the 911’s (12 vs. 10 years).

BMW pays for scheduled maintenance on the M3 for 4 years and 50,000 miles. BMW will pay for oil changes, tire rotation, lubrication and any other scheduled maintenance. Porsche doesn’t pay scheduled maintenance for the 911.

There are over 74 percent more BMW dealers than there are Porsche dealers, which makes it much easier to get service under the M3’s warranty.

Reliability Comparison

To reliably power the ignition and other systems and to recharge the battery, the M3 has a standard 180-amp alternator. The 911’s 150-amp alternator isn’t as powerful.

To reliably start during all conditions and help handle large electrical loads, the M3 has a standard 570-amp battery. The 911’s 340-amp battery isn’t as powerful.

The battery on the M3 is in the trunk, which protects it from hot underhood temperatures which can degrade battery life. By keeping the M3’s battery 20 to 30 degrees cooler, its life is increased by years. The 911’s battery is in the hot engine compartment.

Brakes and Stopping Comparison

For better stopping power the M3’s standard brake rotors are larger than those on the 911:

M3

911

Front Rotors

14.2 inches

13 inches

Rear Rotors

13.8 inches

13 inches

The M3’s brakes have 9% more swept area (the area covered by the brake pads) than the 911 with its standard brakes (694 vs. 634 square inches), so the M3 has more braking power available.

The M3 stops much shorter than the 911:

M3

911

80 to 0 MPH

195 feet

201 feet

Road & Track

70 to 0 MPH

153 feet

162 feet

Car and Driver

60 to 0 MPH

105 feet

116 feet

Motor Trend

Suspension and Handling Comparison

The M3 has vehicle speed sensitive variable-assist power steering, for low-effort parking, better control at highway speeds and during hard cornering, and a better feel of the road. The 911 doesn’t offer variable-assist power steering.

For a smoother ride and more stable handling, the M3’s wheelbase is 16.2 inches longer than on the 911 (108.7 inches vs. 92.5 inches).

For better handling and stability, the track (width between the wheels) on the M3 is 1.9 inches wider in the front than the average track on the 911.

The M3’s front to rear weight distribution is more even (51.2% to 48.8%) than the 911’s (39.8% to 60.2%). This gives the M3 more stable handling and braking.

The M3 Coupe handles at .97 G’s, while the 911 Turbo Coupe Carrera 4 pulls only .91 G’s of cornering force in a Car and Driver skidpad test.

Chassis Comparison

The M3's standard power retractable hardtop allows a seamless transition from an open car, to a completely sealed coupe. The 911 doesn't offer a retractable hardtop.

As tested by AutoWeek, the interior of the M3 Coupe is quieter than the 911 Turbo Coupe Carrera 4:

M3

911

At idle

53 dB

58 dB

Full-Throttle

82 dB

88 dB

60 MPH Cruising

65 dB

80 dB

Passenger Space Comparison

Because it has more passenger and cargo room, the M3 Coupe is rated a Subcompact car by the EPA, while the 911 Coupe is rated a Minicompact. The M3 Convertible is rated a Subcompact car by the EPA, while the 911 Cabriolet is rated a Minicompact.

The M3 Sedan has standard seating for 5 passengers; the 911 can only carry 4.

The M3 Coupe has 24.5 cubic feet more passenger volume than the 911 (88.5 vs. 64).

The M3 Coupe has .1 inches more front headroom and 5.9 inches more front shoulder room than the 911 Coupe.

The M3 Convertible has .2 inches more front headroom and 3.8 inches more front shoulder room than the 911 Cabriolet.

Cargo Capacity Comparison

The M3 Coupe has a much larger trunk than the 911 Coupe (11.1 vs. 4.8 cubic feet).

The M3 Convertible has a much larger trunk with its top down than the 911 Cabriolet (7.4 vs. 4.8 cubic feet).

Ergonomics Comparison

The M3’s standard easy entry system glides the driver’s seat back, making it easier for the driver to get in and out. The 911 doesn’t offer an easy entry system.

The M3’s standard power windows have a locking feature to keep children in the rear seat from operating them. Porsche does not offer a locking feature on the 911’s power windows.

If the windows are left down on the M3 the driver can raise them all using the key in the outside lock cylinder; on a hot day the driver can lower the windows. The driver of the 911 can’t use the remote to operate the windows.

The M3 has a standard automatic headlight on/off feature. When the ignition is on, the headlights automatically turn on at dusk and off after dawn. The 911 doesn’t offer automatic headlights.

While driving with high-beams on, sensitive light sensors available for the M3 detect other vehicles which could be blinded and automatically switch to low-beams. The 911 doesn’t offer automatic dimming high-beams.

A power rear sun shade is optional in the M3 Sedan/Coupe to help block heat and glare for the rear passengers. The 911 doesn’t offer a rear sun shade.

The M3’s standard dual zone air conditioning allows the driver and front passenger to choose two completely different temperatures so people with different temperature preferences won’t have to compromise. This makes both the driver and front passenger as comfortable as possible. The 911 doesn’t offer dual zone air conditioning.

The M3’s available GPS navigation system has a real-time traffic update feature that offers alternative routes to automatically bypass traffic problems. (Service available in a limited number of metro areas.) The 911’s available navigation system doesn’t offer real-time traffic updates.

Wireless connectivity is optional on the M3, connecting the driver and passenger’s cell phones to the vehicle systems. This allows them to use the vehicle’s stereo and hand controls to place calls safely and easily. Porsche doesn’t offer wireless connectivity on the 911.

Economic Advantages Comparison

Insurance will cost less for the M3 owner. The Complete Car Cost Guide estimates that insurance for the M3 will cost $2870 to $10818 less than the 911 over a five-year period.

Intellichoice estimates that five-year ownership costs (depreciation, financing, insurance, fuel, fees, repairs and maintenance) for the BMW M3 will be $17503 to $53480 less than for the Porsche 911.

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